Clock base



FIG. 1 is a top and right front perspective view of a clock base showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof, the rear being substantially similar;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a clock base, as shown and described above. 